Electrolytic cell for the production of aluminum



` Nov. 23, 1965 l H. WUNDERLI 3,219,570

ELECTROLYTIC CELL FOR THE PRODUCTION OF ALUMINUM Filed DeG. 14, 1961 2 Sheets-Sheet 1 L TELL.

BY my, W4

ATTORN 5 Nov. 23, 1965 H, WUNDERL, 3,219,570

ELECTROLYTIC CELL FOR THE PRODUCTION OF ALUMINUM Filed Dec, 14, 1961 2 Sheets-Sheet 2 Tuz.

TORN YS United States Patent O 3,219,570 ELECTROLYTIC CELL FR THE PRODUCTIN F ALUMINUM Heinrich Wunder-li, Zurich, Switzerland, assigner to Schweizerische Aluminium A.G. (Aluminium Suisse SA.) (Alluminio Svizzero S.A.) (Swiss Aluminum Ltd.)

Filed Dec. 14, 1961, Ser. No. 159,226 Claims priority, application Switzerland, Dec. 23, 1960, 14,371 4 Claims. (Cl. 204-225) The present invention relates to an electrolytic cell for producing aluminum.

Electrolytic cells for the production of aluminum in fused baths usually comprise a cat hodic pot in which a fused fluoride bath in maintained and one or more carbon anodes carried by upright rods arranged in rows from one end of the pot to the other. Whether the anodes are prebaked or self-baking, they are burnt away as the production of aluminum proceeds and they are therefore lowered from time to time. For that purpose, the anode carrying rods are vertically movable endwise and usually are aflixed to a horizontal current conductor which is carried by lifting mechanisms mounted on separate supporting frames spanning the pot transversly.

During the various operations which must be carried out such as breaking the crust that forms on the bath, in troducing alumina and distributing it over the crust, tapping off metal, servicing the anodes, and generally servicing the furnace, the supporting frames for the current conductor get in the way of the operators, impede access to the pots and render it difficult to rnechanize the various operations.

One object of the present invention is to provide a new and improved electrolytic cell for producing aluminum which avoids the drawbacks of the prior art described.

In accordance with certain features of the present invention, a fixed current-conducting frame spans the pot from one end to the other. Upright anode rods are arranged in rows and the anode rods in each row are carried by a contact bar parallel to and outside the fixed frame. The contact bars are electrically connected to the fixed frame by flexible conductors and are vertically moved by mechanisms mounted on the frame. Thus, the separate supporting frames previously used are dispensed with.

In accordance with more specific aspects of the present invention, the fixed current-conducting frame comprises vertical conductors at opposite ends of the cell' and a horizontal conductor extending between them and advantageously comprising two horizontal beams on opposite sides of the vertical conductors and extending from one l vertical conductor to the other. These vertical conductors are in effect the legs of the frame by which the anode rods are carried.

Various other objects, features and advantages of the present invention are apparent from the following description and from the accompanying drawings, in which FIG. 1 shows the cell embodying the present invention partly in side elevation and partly in central vertical section;

FIG. 2 is a plan view of the cell; and

FIG. 3 is an end elevation of the cell partly in section.

Referring to the drawings, the cell comprises a pot 1 having a carbon lining 1a with a base through which cathode bars 3 extend, and prebaked carbon anodes 2 adapted to extend into the electrolytic bath. The current flows from the carbon anodes 2 to the carbon lining 1a of the pot and thence to the cathode bars 3 which are joined by bus bars 4. The electrolytic cell shown is one of a row of similar cells, the longitudinal axis of each cell being transverse to the center line of the row of cells.

In each cell, there is a fixed current-conducting frame comprising a vertical conductor 5 at each end mounted on a pedestal 8 and two beams 6 spanning the pot from one end to the other and welded to the outer faces of the vertical conductors. The bus bars 4 joining the cathode bars 3 of one cell extend to the next cell and are there welded to the verticalI conductors 5.

In the cell, the anodes 2 are arranged in pairs, and the pairs are themselves arranged in two rows extending from one end of the pot to the other. The anodes 2 are thereby arranged into four parallel rows, two on each side of the longitudinal median line or axis of the cell. Each pair of anodes 2 is carried by a support 17 on the lower end of an upright anode rod 9. There are two rows of anode rods 9 on opposite sides of the longitudinal median line or axis of the cell, and all the rods in each row are afhxed by screws or clamps (not shown) to a horizontal contact bar 7 of aluminum firmly secured to an iron girder 10, so that all of the anode rods in each row are connected together for vertical movement in unison.

Each girder 10 and therefore the corresponding contact bar 7 is carried by two mechanisms 11 by which said girder and contact bar can be moved vertically. These mechanisms 11 are supported by frameworks affixed tothe top of the fixed current-conducting frame. Each of these frameworks comprises a cross-bar 16, vertical members 18 depending therefrom and secured thereto and cross-bars 19 affixed to said vertical members and to the upper surfaces of the beams 6. 'Ihe mechanisms 11 are preferably in the form of screw jacks to raise and lower the contact bars 7 with the anode rods 9, and include driving motors 21, mounted on the fixed current-conducting frame near opposite ends -of the cell and connected to the jacks by suitable gear and shaft transmissions. In the specific form shown, each motor 21 drives a pair of shafts 11a, each of which in turn drives a gear (not shown) in a casing 11b having a threaded engagement with a threaded spindle 11C secured to the corresponding girder 10 and Contact 7, so that as this gear rotates, it moves the spindle vertically and thereby moves the anode rods 9 with their supported anode 2 vertically in unison.

Looped flexible conductors 12, each welded at one end to the fixed current-conducting frame and at the other end to the corresponding contact bar 7, serve to supply current from this frame to the anodes 2, while permitting the anodes to move vertically a limited amount. The points of connection between the flexible conductors 12 and the contact bars 7 lie between adjacent rods 9.

The fixed current-conducting frame is preferably composed of an aluminum-iron alloy containing from 1.8 to 2.0% iron, because this alloy can very easily be cast, is strong, and has a conductivity only a little less than that of pure aluminum. The vertical conductors 5 forming part of this fixed frame may be sand-cast or chill-cast, but the beams 6 also constituting part of said frame are preferably simple sections produc-ed by continuous casting.

During the operation of the cell, the anodes 2, as they are burnt away, are lowered into the melt by operation of the mechanisms 11. If .an individual anode 2 must be replaced by a new one, the clamp or other means by which the anode rod is fixed to the Contact bar 7 is released to enable what is left of the anode to be withdrawn.

When the anodes 2 are lowered, the flexible connectors 12 and the lifting mechanisms 11 allow only limited vertical travel. To enable the anodes 2 to have greater vertical travel than is permitted by the lifting mechanisms 11 and/or the flexible connectors 12, auxiliary contact bars 13 are provided on both sides of the fixed frame. These auxiliary Contact bars 13 rest on cross-beams 14 affixed to the fixed frame and are electrically connected t-o the beams 6 by electrical connections 15. The auxiliary contact bars 13 resemble the contact bars 7 and are supported by iron girders 20 secured to the cross-beams 14. When the contact bars 7 cannot be lowered any more because the limit of downward travel permitted by the mechanisms 11 and/ or the flexible connectors 12 has been reached, the anode rods 9 are temporarily clamped to the auxiliary contact bars 13, so that they are supported by the bars 13 and girders 20, and disconnected from the contact bars 7. The contact bars 7 can then be lifted by reverse lifting operation of the mechanisms 11, Without interrupting the current to the anodes 2 and while supporting the anodes, the rods 9 can once more be secured to said bars, so that the anodes can be lowered still further, after the rods are disconnected from the auxiliary contact bars 13.

Although in the cell shown, the anodes 2 are prebaked, the invention can also employ cells having self-baking anodes.

While the invention '-has been described with particular reference to a specific embodiment, it is to be understood that it is not to be limited thereto but is to be construed broadly and restricted solely `by the scope of the appended Vthe cell to the other, contact barsextending along and on the outside of said -frame and supported from said frame, the anode rods in each row having an-electrical connection to a correspondingfone of said contact bars and being supported for Vvertical movement in unison with the latter contact bar, flexible electrical conductors connecting said contact bars to said frame at regions between the ends of the-cell, and -means supported on said frame for moving said anode rods with said contact bars vertically.

2. An electrolytic cell as described in claim 1, wherein the xed frame has end supports serving also as conductors, each of said supports being in the form of a single column-like upstanding member substantially in a central vertical longitudinal plane of the cell at each end of the cell, and ltwo horizontal beams on opposite sides of the supports secured thereto and extending from one support to the other longitudinally of the cell.

3. An electrolytic cell according to claim 1, comprising means for releasably connecting said anode rods and said contact bars for Vertical movement in unison, and releasable means for temporarily supporting said anode rods while said contact bars are being raised and for supplying current to said anode rods independently of said contact bars and comprising a lixed auxiliary contact bar supported from .said iixed frame located beneath each of the movable contact bars and having an electrical connection to the iixed frame.

4. An electrolytic cell according to claim 1, said fixed frame being composed of an aluminum iron alloy containing from 1.8 to 2.0% iron.

References Cited by the Examiner UNITED STATES PATENTS 2,857,545 10/ 1958 Wunderli 204-67 2,930,746 3/ 1960 Cooper 204-244 2,939,829 6/1960 Allen 204-243 2,958,641 11/1960 YReynolds 204-243 FOREIGN `PAT ENT S 607,981 11/1960 Canada.

69,402 7/ 1945 Norway.

WINSTON A. DOUGLAS, Primary Examiner.

JOHN R. SPECK, JOHN H. MACK, Examiners. 

1. AN ELECTROLYTIC CELL FOR THE PRODUCTION OF ALUMINUM IN A FUSED BATH CONTAINED IN A CATHODIC POT, COMPRISING A FIXED CURRENT-CONDUCTING FRAME SPANNING THE POT FROM ONE END TO THE OTHER, ANODES ADAPTED TO EXTEND INTO SAID BATH, VERTICALLY MOVABLE UPRIGHT ANODE RODS ON THE OUTSIDE OF SAID FRAME SUPPORTED FROM SAID FRAME AND CARRYING SAID ANODES, SAID RODS BEING ARRANGED IN ROWS FROM ONE END OF THE CELL TO THE OTHER, CONTACT BARS EXTENDING ALONG AND ON THE OUTSIDE OF SAID FRAME AND SUPPORTED FROM SAID FRAME, THE ANODE RODS IN EACH ROW HAVING AN ELECTRICAL CONNECTION TO A CORRESPONDING ONE OF SAID CONTACT BARS AND BEING SUPPORTED FOR VERTICAL MOVEMENT IN UNISON WITH THE LATTER CONTACT BAR, FLEXIBLE ELECTRICAL CONDUCTORS CONNECTING SAID CONTACT BARS TO SAID FRAME AT REGIONS BETWEEN THE ENDS OF THE CELL, AND MEANS SUPPORTED TO SAID FRAME FOR MOVING SAID ANODE RODS WITH SAID CONTACT BARS VERTICALLY. 